Posted on January 2, 2023 (Updated on July 10, 2025)

Calculating global horizontal irradiance (GHI) from surface solar radiation downwards from the ERA5 data

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How do you calculate global horizontal irradiance?

Global Horizontal Irradiance (GHI), from the hemisphere above a horizontal plane surface, is a combination of DNI, corrected for the angle of incidence of the beam (θ), and Diffuse Horizontal Irradiance (DHI). GHI = DNI*cosθ + DHI. All these parameters are measured in units of W/m2.
Apr 1, 2013

How do you calculate GHI?

GHI scores are calculated using a three-step process:

  1. Prevalence of undernourishment80. x100 = standardized undernourishment value.
  2. Child stunting rate70. x100 = standardized child stunting value.
  3. Child wasting rate30. x100 = standardized child wasting value.
  4. Child mortality rate35. x100 = standardized child mortality value.


What is global horizontal irradiance GHI?

GHI is defined as the total amount of shortwave terrestrial irradiance received by a surface horizontal to the ground. From: Standalone Photovoltaic (PV) Systems for Disaster Relief and Remote Areas, 2017.

How do you calculate diffuse horizontal irradiance?

A fair estimate of the diffuse irradiance can be obtained by subtracting the direct normal beam radiation projected onto a horizontal surface from the global irradiance.
Mar 28, 2022

How do you calculate solar irradiance?

Tools for Calculating Solar Irradiance

  1. 1 – Pyrheliometers. A pyrheliometer is used to measure direct radiation from the sun.
  2. 2 – Pyranometers. Like pyrheliometers, pyranometers measure sun exposure.
  3. 3 – Net Radiometers. Not really used for solar installation, net radiometers can measure incoming radiation.

Aug 25, 2022

What is GHI value?

Global Horizontal Irradiance (GHI) is the total amount of shortwave radiation received from above by a surface horizontal to the ground. This value is of particular interest to photovoltaic installations and includes both Direct Normal Irradiance (DNI) and Diffuse Horizontal Irradiance (DIF).

What is a GHI score?

The Global Hunger Index (GHI) is a tool designed to comprehensively measure and track hunger at global, regional, and national levels. GHI scores are calculated each year to assess progress and setbacks in combating hunger.

What is GHI and DHI?

The global horizontal irradiance (GHI) falling onto the Earth’s surface consists of the diffuse horizontal irradiance (DHI) from the sky and the direct normal irradiance (DNI) from the sun. GHI = DHI + DNI*cos(θ) where θ is the solar zenith angle (vertically above the location is 0°, horizontal is 90°).
Jul 2, 2013

How is irradiance of LED calculated?

The irradiance pattern over a flat irradiated surface in front of the LED, at the target plane (Figure 1(a)), can be calculated by making cosθs=cosθ.
Feb 18, 2021